Remove PositionFirstComponent

gap-system · Sep 15, 2018 · 2f6365a · 2f6365a
1 parent 6a81396
commit 2f6365a
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diff --git a/lib/obsolete.gi b/lib/obsolete.gi
@@ -795,88 +795,6 @@ end);
 # 
 
 
-#############################################################################
-##
-#M  PositionFirstComponent( <list>, <obj>  ) . . . . . . various
-##
-##  kernel method will TRY_NEXT if any of the sublists are not
-##  plain lists.
-##
-##  Note that we use PositionSorted rather than Position semantics
-##
-
-## This is deprecate because the following three methods each
-## compute differen things:
-## The first and third both use binary search, but one aborts
-## early on the first entry with first component equal to obj,
-## while the other aborts late, thus always finding the first
-## matching entry. Only the latter behavior matches PositionSorted
-## semantics.
-##
-## The second method on the other hand performs a linear search
-## from the start. This means that it also does not conform to
-## PositioSorted semantics (not even if the input list happens
-## to be sorted). For example, if an entry is not
-## found, it returns Length(list)+1, not the position it should
-## be inserted to ensure the list stays sorted.
-##
-## Fixing this could have broken private third-party code.
-## Since this operations is rather peculiar and can be replaced
-## by PositionSorted(list, [obj]), it was deemed
-## simples to declare it obsolete.
-
-# InstallMethod( PositionFirstComponent,"for dense plain list", true,
-#     [ IsDenseList and IsSortedList and IsPlistRep, IsObject ], 0,
-# function ( list, obj )
-#     Info( InfoObsolete, 1,
-#         "the operation `PositionFirstComponent' is not supported anymore" );
-#     return POSITION_FIRST_COMPONENT_SORTED(list, obj);
-# end);
-# 
-# 
-# InstallMethod( PositionFirstComponent,"for dense list", true,
-#     [ IsDenseList, IsObject ], 0,
-# function ( list, obj )
-# local i;
-#     Info( InfoObsolete, 1,
-#         "the operation `PositionFirstComponent' is not supported anymore" );
-#   i:=1;
-#   while i<=Length(list) do
-#     if list[i][1]=obj then
-#       return i;
-#     fi;
-#     i:=i+1;
-#   od;
-#   return i;
-# end);
-# 
-# InstallMethod( PositionFirstComponent,"for sorted list", true,
-#     [ IsSSortedList, IsObject ], 0,
-# function ( list, obj )
-# local lo,up,s;
-#     Info( InfoObsolete, 1,
-#         "the operation `PositionFirstComponent' is not supported anymore" );
-#   # simple binary search. The entry is in the range [lo..up]
-#   lo:=1;
-#   up:=Length(list);
-#   while lo<up do
-#       s := QuoInt(up+lo,2);
-#       #s:=Int((up+lo)/2);# middle entry
-#     if list[s][1]<obj then
-#       lo:=s+1; # it's not in [lo..s], so take the upper part.
-#     else
-#       up:=s; # So obj<=list[s][1], so the new range is [1..s].
-#     fi;
-#   od;
-#   # now lo=up
-#   return lo;
-# #  if list[lo][1]=obj then
-# #    return lo;
-# #  else
-# #    return fail;
-# #  fi;
-# end );
-
 #############################################################################
 ##
 #M  MultVector( <list1>, <poss1>, <list2>, <poss2>, <mult> )

diff --git a/src/listfunc.c b/src/listfunc.c
@@ -552,36 +552,6 @@ Obj             FuncPOSITION_SORTED_LIST_COMP (
 }
 
 
-Obj             FuncPOSITION_FIRST_COMPONENT_SORTED (
-    Obj                 self,
-    Obj                 list,
-    Obj                 obj)
-{
-  UInt top, bottom,middle;
-  Obj x;
-  Obj l;
-  bottom = 1;
-  top = LEN_PLIST(list);
-  while (bottom <= top) {
-    middle = (top + bottom)/2;
-    l = ELM_PLIST(list,middle);
-    if (!IS_PLIST(l))
-      return TRY_NEXT_METHOD;
-    x = ELM_PLIST(l,1);
-    if (LT(x,obj)) {
-      bottom = middle+1;
-    } else if (LT(obj,x)) {
-      top = middle -1;
-    } else {
-      return INTOBJ_INT(middle);
-    }
-  }
-  return INTOBJ_INT(bottom);
-}
-
-
-
-
 /****************************************************************************
 **
 *F  SORT_LIST( <list> )  . . . . . . . . . . . . . . . . . . . .  sort a list
@@ -1747,7 +1717,6 @@ static StructGVarFunc GVarFuncs [] = {
     GVAR_FUNC(APPEND_LIST_INTR, 2, "list1, list2"),
     GVAR_FUNC(POSITION_SORTED_LIST, 2, "list, obj"),
     GVAR_FUNC(POSITION_SORTED_LIST_COMP, 3, "list, obj, func"),
-    GVAR_FUNC(POSITION_FIRST_COMPONENT_SORTED, 2, "list, obj"),
     GVAR_FUNC(SORT_LIST, 1, "list"),
     GVAR_FUNC(STABLE_SORT_LIST, 1, "list"),
     GVAR_FUNC(SORT_LIST_COMP, 2, "list, func"),